Electricity meters, or simply meters, are devices, that among other things, measure electrical energy consumed by a residence, factory, commercial establishment or other such facility. Electrical utilities rely on meters for many purposes, including billing customers and tracking demand for electrical power. A common form of meter utilizes current transformers to sense the electrical current being supplied to the facility being metered. The current sensed by the current transformers is transmitted to circuit boards included in the meter to facilitate measurement of the amount of electrical energy being consumed by the facility.
A typical electricity meter includes several electrical components, ranging in size from relatively large power busses and transformers to microelectronic devices. Because of the variety of components within meters, labor and cost associated with assembling electricity meters can be a limiting factor in cost of electricity meters.
For example, electricity meters require heavy duty, thick copper current blades that are received by the meter housing to allow the meter to be coupled to the electrical power lines. These blades must in turn be connected to conductors, called current coils, that provide current signals to a current transformer within the meter. These coils can include multiple components that are assembled, for example, the thick copper blades and an insulated wire. The assembly of such current coils creates additional component and labor cost. One approach that reduces the costs associated with manufacturing current coils involves a single piece current coil formed from a conductive metal bar.
Prior art single piece current coils typically were formed as a flat bar formed in the shape of a “C”. While the such single piece current coils were less expensive generally than assembled coils, they did not accommodate many types of meters due to the rigid “C” shape. Even in meters that are amenable to the “C” shaped coils, the shape of the coils occupied significant vertical space within the meter, which reduced the flexibility of component layout within the meter housing. To address this issue, other rigid current coils were formed into unique serpentine shapes that optimized circuit layout.
While each of the above single piece coils has particular usefulness, there is need for even greater efficiency in the manufacture and use of current coils and blades within an electricity meter.
Another issue with current coils relates to voltage measurements. In particular, voltage measurements are typically obtained from the current coils, thereby requiring connection to yet another, thinner lead wire that is also connected to a circuit board where the digital processing circuit is located. All of the various interconnections, including the connection to the thin lead wire to both the current coil and the lead wire, are labor intensive.
As a consequence, there is a need for a more efficient methods and arrangements for connecting current coils within an electricity meter.